Emerging Technologies for the Production of Ultraclean IGCC Syngas

Transcription

1 Emerging Technologies for the Production of Ultraclean IGCC Syngas R. Gupta, B.S. Turk, T.C. Merkel and A. Lopez-Ortiz Research Triangle Institute RTP, NC 2001 Gasification Technologies Conference October 7-10, 2001

2 Driving Force Vision 21 Energyplex Coal Other Fuels POWER F u e l C e l l H ig h E f f ic ie n c y T u r b in e FU ELS Oxygen Membrane Gasification Gas Stream Cleanup Hydrogen Separation L iq u i d s C o n v e r s io n Process Heat/ Steam CO2 Sequestration Gas stream cleanup Near-zero (ppb) emission limits Modular design Power/electricity + Fuel cells + Turbines Fuels/chemicals Fuels/Chemicals Ele ctricity

3 Contaminant Tolerance Limits Contaminants Tolerance Limits (by Volume) Fuel Cells Chemical Production MCFC PAFC SOFC Total Sulfurs 60 ppb <0.5 ppm <50 ppm <0.1 ppm Total Halides 10 ppb <0.5 ppm NS <1 ppm Ammonia NS <1 vol% 0.2 vol% <5,000 ppm NS - Not Specified

4 Technology Development Approach

5 Technology Development Approach (Bulk Desulfurization)

6 Permeability of Syngas Components in a Solubility Selective Membrane 10 5 PDMS 23 C Permeability, Barrers H 2 CO CH 4 CO 2 COS H 2 S SO 2 N T c, K NH 3 H 2 O

7 Acid-Gas Separation in a Polymer Membrane Module

8 Schematic of Gas Permeation Apparatus at RTI Pressure gauge Feed high-pressure cylinder Pressure regulator MFC Pressure Regulator Residue Temperature control Membrane cell Permeate He Sweep MFC GC Vent to atmosphere

9 Gas Permeation System at RTI

10 Summary of Acid Gas Permeation Results at Room Temperature Polymer CO Mixed Gas Selectivity 2 Permeability (Barriers) CO 2 /H 2 H 2 S/H 2 PDMS Medal Medal Medal Medal Medal Medal Medal Medal Medal Medal Medal Medal Medal Medal Pebax

11 Mixed-gas H 2 S/H 2 Selectivity as a Function of Temperature Mixed-gas Selectivity, CO 2 /H PDMS Medal 001 Medal 002 Medal 003 Medal 004 Medal 005 Medal 006 Medal 007 Medal 016 Medal 017 Medal Temperature, C

12 Membrane Simulation Countercurrent, Shell-Side Feed Feed: T = 25 C, P = 600 psia Residue A = 377 m 2 Permeate: P = 20 psia 500,000 fibers, ID = 150 µm OD = 300 µm, L = 1 m Component Feed mole fraction Permeance (GPU)* H CO N CO H 2 S H 2 O * Permeance values based on H 2 flux of 10 gpu [10-5 cm 3 (STP)/(cm 2 s cm Hg)] and the current best case room temperature selectivities. Membrane simulator reference: Coker, D.T., Freeman, B.D., and Fleming, G.K., AIChE Journal, Vol. 44, No. 6, June (1998)]

13 Simulation Results decreasing feed flow rate increasing stage cut % of Inlet H 2 in Permeate ppm H 2 S in Residue % of Inlet CO 2 Removed in Permeate % of Inlet H 2 S Removed in Permeate

14 Membrane Simulation H 2 S Removal 50 Percent H 2 in Permeate S = 50 S = 40 S = Percent H 2 S Removed in Permeate

15 Summary of Bulk Desulfurization Testing (polymer membranes) Process Membranes can separate H 2 S, COS, CS 2 in addition to CO 2, H 2 O, HCl and NH 3 Selectivity is strongly dependent on temperature Simulations indicate that 80 to 90% H 2 S removal without appreciable loss of H 2 Materials Films with selectivities of H 2 S/H 2 >30 were synthesized These polymer compositions are readily adaptable to hollow fiber production for membrane modules

16 Technology Development Approach (Polishing Desulfurization)

17 Comparison of Various Sulfur Polishing Steps Desulfurization Sub-ppm Kinetics Removal Capacity Regenerability Cost ZnO Guard Bed Activated Carbon + + Monoliths Regenerable Sorbents (RVS)

18 Bench-Scale Facility for Monolith Testing at RTI

19 Sulfur Removal by Monolith Sorbents H2S Effleunt Concentration (ppmv) Sulfidation Conditions Pressure: 280 psig Temperature: 1,000 F Space Velocity: 2,000 h -1 Cycle 1 Cycle 2 Cycle 3 Cycle 4 Proposed Limit Time (min)

20 Desulfurization Performance between 200 and 1,000 F for Monolithic Sorbents H2S Leak (ppmv) Sulfidation Conditions Pressure: 280 psig Space Velocity: 2,000 h -1 H 2 S Feed Concentration: 5,000 ppmv H2S leak, ppm Sulfur Load, g Sulfur Load (wt%) Temperature ( F)

21 H 2 S Removal Using RVS-1 Sorbent H2S (ppm), Wet Basis 20,000 18,000 16,000 14,000 12,000 10,000 8, , , ,000 2 Sulfidation Conditions: Pressure: 450 psig Temperature: F Feed Gas composition (vol, %) CO 18.9 CO H H 2 S 1.0 (10,000 ppmv) H 2 O 63.0 Cycle 1 Cycle 2 Cycle 3 Cycle 4 Cycle 5 Cycle Time (min)

22 Summary of Polishing Desulfurization Work Two sets of materials tested for H 2 S removal to <1 ppmv These materials are regenerable for multiple cycles They can operate at temperatures as low as 200 F Work is continuing to reduce the sulfur levels down to <100 ppbv

23 Preliminary Process Flowsheet 6 Residue HP Air Intercooling 2-Stage Compressor 3 DSRP Reactor Q = Btu/hr Q = Btu/hr Raw Syngas 1 HTHP Barrier Filter (if needed) 5 B3 7 Q = Btu/hr Monolith 1 Sulfidation Q = 0 Btu/hr 9 H2O HCL NH3 B5 10 Monolith 3 Regeneration Q = Btu/hr Permeate SEP2 Polymer Membrane Module Monolith 3 Heating 13 Q = Btu/hr Q = Btu/hr W = 27 HP 4 POX Reactor Q = Btu/hr Regeneration Gas Q = Btu/hr B CO2 Rich Tail Gas Sulfur HP Air Vent 17 Clean Syngas N2 25 Booster Inert Heating Gas Q = Btu/hr 20 Make up N2 2% O2/N

24 Summary of Material/Energy Balance Description Raw Syngas Clean Syngas Tail Gas Condensate Stream # Temperature ( F) Pressure (psia) Total Flow (lbmol/hr) Mole Fraction H PPM 2 PPB CO CO N H 2 S 8000 PPM 392 PPB 76 PPM 245 PPM NH PPB H 2 O HCl 299 PPM 3 PPB LHV (Btu/scf) Generated using laboratory and bench-scale test data collected and the ASPEN simulation software at RTI and the membrane simulator at NCSU

25 Nexant Evaluation Evaluated the design information supplied by RTI Sized equipments and estimated their cost for a 500-MWe IGCC based on Texaco gasifier Used the Rectisol process as a benchmark for cost comparison

26 Results of Nexant Evaluation Total Sulfur Installed Removal Cost Process Target 2001 $ MDEA 70 ppm $18M 1 Rectisol <1 ppm $75M RTI <1ppm $42M 2 1 Does not include the cost of COS hydrolysis reactor. 2 Future improvements in membrane and sorbent materials are expected to lower this number significantly.

27 Potential Impact of this Technology Significant cost advantage for sulfur removal RTI vs. Rectisol Enrichment of Btu content of syngas without pressure loss Significant concentration of CO 2 in the tail gas stream Highly modular Highly integrated overall contaminant control Individual process components for specialized treatment

28 Conclusions/Future Steps Feasibility of RTI s syngas desulfurization process confirmed at laboratory scale Preliminary economic evaluation indicates 75% lower installed cost than a Rectisol system In Phase II work, membrane modules of 1 ft 2 will be tested at bench-scale, and plans are being made to test a 150 ft 2 module with real syngas Both monolith and sorbent materials are being advanced to reduce the sulfur levels to <100 ppbv

29 Acknowledgments DOE/NETL funded this research through contract No. DE-AC26-99FT40675 MEDAL North Carolina State University Süd-Chemie Prototech Inc. SRI International Nexant, Inc. Texaco Power and Gasification